Fix `status_check_contexts` matching bug (#28582)
Fix #28570
Follow #24633
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Copied from
https://github.com/go-gitea/gitea/issues/28570#issuecomment-1867327999
The feature introduced in #24633 should be compatible with
`status_check_contexts`. However, if one or more of
`status_check_contexts` is not a legal glob expressions, `glob.Compile`
will fail and the contexts cannot match.
https://github.com/go-gitea/gitea/blob/21229ed2c8ed00f57100adf9ebc5f4a08da9a66e/routers/web/repo/pull.go#L653-L663